The present invention relates to programmable power circuit control timers of the type which has its most important commercial application as a timer for controlling the energization and de-energization of lighting circuits in a home or the like for security purposes, although certain aspects thereof have a more general application. In such a commercial application, the present invention will form a programmable power circuit control timer of the type to be connected in series with a power cord for a table lamp or the like, in which case it can be incorporated in a self-contained housing adapted to rest on the top of a table, or, in its most preferred form, it is so compact as to be mountable in an existing toggle wall switch opening in place of the toggle switch, and has programming and power on and off controls mounted on the front of one switch station of a single or multiple station wall switch cover plate. A unique timer of this type is disclosed in said copending application Ser. No. 22,453, filed Mar. 21, 1979.
(Our) U.S. patent application Ser. No. 22,453, filed Mar. 21, 1979, describes an electronic timer and power control system in which a shift register is continuously cycled to cause a daily repetition of ON and OFF periods for the control of lights and appliances or the like. The ON and OFF pattern of operation is determined by storing power circuit ON "1" and OFF "0" control markers respectively in each of the storage locations of the shift register. At any given instant of time each storage location in the register represents a definite time interval in the 24 hour cycle, such as one-quarter hour. (The time interval represented by such storage location advances one time interval as the shift register markers are shifted one position.) The control markers can be entered into the storage locations either synchronously, in real time over a 24 hour period, or asynchronously in a relatively short time by manual means.
This application discloses a number of different forms of such a system. The most commercially important form thereof is an extremely low cost 24 hour repeat cycle timer of such small size that it can be completely contained within the small space of an electrical flush switch-receiving box commonly employed to house a wall mounted toggle light switch unit. The front control portion of the timer is also of such small size that it fits over one switch station of any conventional single or multi-station switch cover plate without interfering with the toggle switch of the adjacent station in the latter case.
To accomplish the above objectives, it was necessary to eliminate the usual costly and overly bulky digital read-out and addressing means which prior shift register controlled timers used for identifying and accessing the storage locations during the manual programming of these timers (see Carlson U.S. Pat. No. 4,035,661). Instead of such digital read-out means, the storage locations of the wall switch timer disclosed in our application is most advantageously indicated on the dial of a preferably rotatable and depressible time dial knob which has a discrete number of detented indexable positions. Each detented postion of the knob corresponds to a single memory storage location in the shift register. When the knob is rotated, the movement of the knob to each detent position generates a shift pulse that clocks the shift register and advances all markers to the next storage location.
For a 24 hour repeat-cycle timer capable of switching a light or appliance ON or OFF, if each basic timing interval is one-quarter hour, 96 memory storage locations are required in the shift register. In the form of the invention disclosed in our application, the time dial knob when depressed forms a push button control for operating the light circuit involved and programming the timer. Also, it has 48 detent positions so that the knob must be rotated through two complete revolutions to clock the shift register through one complete cycle. This permits the time dial knob to be marked with the familiar 1 to 12 hour indicia like a clock face, with 1/4 hour markers placed between the hour markers. An AM-PM indicator adjacent the knob changes when the knob is rotated past the 12 hour indicia. Thus, each index mark on the dial corresponds to a specific quarter-hour, further identified with the particular AM or PM indication on the indicator. This timer is simply programmed by first setting the time dial knob to a present time setting relative to an index mark on the face plate of the timer and then momentarily depressing the knob and the shaft to which it is connected to change the condition of the light circuit involved to the desired condition. Depression of the knob operates a sequence switch which alternately produces voltages which either enter a "1" on marker or leaves a "0" marker in the first stage of the shift register. As the knob is then advanced to its various other positions, the previously set marker is merely duplicated in the first stage of the shift register until a further change in the condition of the light circuit is desired. This greatly reduces the complexity and tedium of setting a manual program into the timer of our invention, as compared, for example, to the previously described relatively costly and bulky digital readout and shift register addressing system as utilized in the Carlson U.S. Pat. No. 4,035,661.
For automatic operation of the timer, the shift register is clocked synchronously in real time by quarter-hour pulses derived from the 60 Hz AC supply. The light circuit involved will be turned ON or OFF by the "1" and "0" markers in the last stage of the shift register for each quarter-hour period involved.
Once the timer has been programmed and is properly synchronized with real time, it is advantageous to provide an indication to the user which enables him to examine the contents of the shift register memory locations. In a timer for home use of this type, it is advantageous to be able to review the program to be assured that the control operations will take place at the desired times. In the timer disclosed in (our) said application Ser. No. 22,453, such an indication is available only within the first time interval (which is there 15 minutes) by advancing the knob through the various time interval positions and noting the results thereof on the lights which are controlled by the timer or a green indicator light.
While the depressible and rotatable knob just described can be used in a similar manner for either effecting a rapid asynchronous programming of the timer or for rapidly reviewing the program, there are still a number of problems associated with these operations which make their use difficult for many persons and could result in errors of operation or non-functioning of the timer. The nature of these problems and the means provided to minimize them will now be described.
It should be recognized that in complying with the physical size limitations as described above, and satisfying the requirement for use with and upon a standard switch cover plate, severe limitations are placed on the number of controls and indicators available to the user. In the commercially practical realization of the invention, and in accordance with one of the improvement features of our present invention, it was found advantageous to provide only a single indicator light to show the status of the timer, a two rather than a three position switch as described in our application for turning the timer ON and OFF and clearing the memory, and a single time dial knob that could be both rotated and depressed. With these controls and indicator, it is most desirable to perform and indicate the status of most and preferably all of the following functions and modes:
1. Provide a timer ON-OFF switch to CLEAR (reset) the memory and to provide an "air-gap" electrical disconnect for safety purposes required by the Underwriter's Laboratory Standards; PA1 2. Indicate the NOT PROGRAMMED and PROGRAMMED status of the program; PA1 3. Change and indicate AUTOMATIC (timed) operation and MANUAL (not-timed) operation operating modes; PA1 4. Manually control the light at all times without disturbing the stored program; PA1 5. Initiate a real-time 24 hour synchronous program period; PA1 6. Terminate a real-time 24 hour program period; PA1 7. Initiate a rapid manual asynchronous program entry mode; PA1 8. Terminate a rapid manual asynchronous program mode when completed; PA1 9. Initiate a program review mode; and PA1 10. Terminate a program review mode. PA1 (1) the indicator light had previously been flashing to indicate that the shift register storage locations had been cleared and was ready to accept a new program; PA1 (2) the time dial knob had been moved (to set present time); and PA1 (3) the time dial knob had been depressed to "enter" present time.
In attempting to "human engineer" the timer to best satisfy the above requirements within the limitations shown above, many previously mentioned problems occur. Firstly, in using the time dial knob for rapid asynchronous programming or reviewing the program it is necessary to synchronize the indexed dial mark corresponding to the present real time with the last marker storage location so that all the marker storage locations will correspond in real time with the dial knob time indications. This operation is explained to the user as "setting present time" so that whenever the time dial is to be used he would realize that the first step he is instructed to do is to set present time on the dial knob and then "enter" that time by pressing the knob. "Entering" present time by depressing the time knob should not change the state of the light or enter a "1" marker in the shift register (which does so in the timer disclosed in our Application Ser. No. 22,453.
Secondly, in entering a manual program by using the time setting dial it was found that many users had difficulty if present real time was located within a longer time interval during which they wanted to have the light ON. For instance, if the time was 8:00 PM when the user desired to program the timer and he wanted the light ON from 5:30 PM to 11:00 PM, he would have to set the dial to 8:00 PM and depress the dial knob to "enter" present time. Then he would have to press it again without rotating the dial knob to turn the light ON, since present time represented a desired ON time.
To complete his program, he would then have to advance the dial knob to 11:00 PM, depress the time dial knob to turn the light OFF, advance again to 5:30 PM, turn the light ON and advance again to 8:00 PM to complete the 24 hour cycle. This last operation, the joining up of the early segment of an ON interval preceeding present time with that portion of the ON interval following present time, seemed to be a source of considerable confusion.
In accordance with another feature of our present invention, to simplify the operation so that the user can ignore the location of "present time" with respect to a desired ON interval, a system was devised that permitted the user to employ a uniform sequence of operation no matter where present time was located. Thus he could think of actions that always involved first rotating the dial knob to a desired time (present time, "ON" time or "OFF" time) and then pressing the knob to "enter" that time. It was found that the user learned this sequence much more rapidly and easily, because it allowed each dial setting to be associated with a single direction
(1) ENTER PRESENT TIME, PA0 (2) ENTER "ON" TIME, or PA0 (3) ENTER "OFF" TIME. After "entering present time" the system permits rotation of the time dial to the first desired ON time. This sequence of time dial knob action is thus always the same, namely to rotate the time dial knob and then depress the same to first enter an "ON" time.
This method of programming is easier, it is believed, because it permits the user to think squentially of (1) "present time", (2) the first desired ON time and (3) the first desired OFF time, (4) the second desired ON time, (5) the second desired OFF time, etc., until he has set as many ON and OFF periods as desired.
The time dial knob is arranged so that it can be turned in one direction only, that is, in the direction that advances the indicated time. When present time is indicated on the time dial knob, it must first be depressed to "enter" present time. This action switches the shift register clock input from a real time pulse source to the output of a pulse switch operated by movement of the dial knob to each shift detected position thereof. There is no restriction on how much the dial knob can be rotated after present time is entered. It can be rotated one step to the first ON time or many complete revolutions to the first ON time. This lack of restriction also aids the user in separating the actions of setting and entering "present time" from the desired first ON and OFF times.
It will be recognized that the above method of programming as so far described will result in the shift register having stage locations containing markers corresponding to the desired ON or OFF condition of the controlled device at the times indicated on the time dial knob. However, when a fully 24 hour period has been programmed in the example program being described, the last location of the shift register will correspond with the time indicated on the dial knob when the first ON marker was stored therein, rather than present time, since it is the appearance of a "1" marker in the last storage location of the shift register that signals completion of a program cycle. In accordance with another feature of the invention, means are provided for automatically advancing the shift register so that it will be automatically advanced until the last storage location corresponds to the time indicated when "present time " was entered. This provides automatic synchronization of the shift register locations with real time. At the same time that this is done, the shift register clock input is switched back to the synchronous real time counter output. Thus the user is freed from any need to synchronize his program with real time beyond the initial entry of present time.
The stated feature that the shift register's last storage location will contain the marker corresponding to the first ON time assumes that the user has completed a 24 hour program cycle by rotating the time dial through two complete revolutions after entering the first "ON" marker. It is likely, however, that he may not have done this. For instance, he may have entered present time at 2:00 PM, then entered a 5:30 PM ON time and 11:00 PM OFF time. Since this may complete his desired program he may neglect to rotate the time dial further. In anticipating of this possibility, in accordance with another feature of the invention, means have been provided in the timer which, after the entry of present time and at least a single ON time followed by an OFF time "wait" five minutes mode of operation is established to allow for further programming, if desired. This means then completes the program with all subsequent timing intervals OFF, and automatically synchronizes the shift register with real time just as if the user had completed the program by rotation of the time dial.
The problem of reviewing the program and returning the shift register to synchronism with real time also involves "human engineering". The review mode of the timer should be possible at any time. In accordance with another feature of the invention, to read out the state of the storage locations of the shift register it is necessary only to clock it through a complete program cycle with the time dial knob after present time is set on the time dial knob and observe the controlled device for an ON or OFF condition at the times indicated on the dial. In order that the storage locations be properly identified with their real times it is necessary to set the time dial knob to the correct present time so that this time will correspond with the last storage location. Then, all the marks on the time dial knob will correspond with the proper storage locations in the shift register for the programmed markers. The review mode is thus started by an "enter present time" operation, namely by pressing the time dial knob after setting the same to the correct present time. This switches the shift register clock input from the real time counter output to a pulser switch output. The time dial knob can then be rotated through a complete cycle to observe the stored program. The cycle can be repeated indefinitely by continuing to rotate the time dial knob. To terminate the review mode the user simply depresses the time dial knob a second time. When the time dial knob is depressed to terminate the review mode, the shift register is automatically clocked by exactly the number of pulses required so that the last storage location thereof will contain the same marker that was present when the review mode was initiated. Thus the shift register is automatically resynchronized with real time. Upon termination of the review mode the timer is placed back into the automatic mode and the indicator light comes on steady. However, to assure that the timer will not be left in the review mode indefinitely if the user fails to terminate review, means is provided which automatically terminates the review mode in approximately 40 seconds if no pulse is received from the pulser switch during that period. It can be seen that the automatic resynchronization of the shift register with real time upon the termination of a review mode makes it impossible for the user to substantially disturb the program as a result of having reviewed the program.
With the constraint in the preferred form of the invention placed upon the number of indicator lights (one) and controls (two) available to the user as explained previously, it became important to use the indicator lamp in a manner that would provide the most useful information to the user. (In the timer disclosed in our application Ser. No. 22,453, a red light is energized during programming and a green light is energized with the light circuit being controlled.) In accordance with another feature of the invention, only one indicator light is provided which has a flashing condition when the timer is on and there are no program markers stored in memory. Since a flashing light is known to attract more attention than a steady light, this condition was selected to signal that there is no program stored in the timer's memory and timed operation will not occur. This feature is particularly useful to call the user's attention to the need to reprogram the timer after a prolonged power failure. (Another feature of our invention is that a power failure of less than a given time like 5 minutes will not cause loss of memory.) A steady-on condition of the indicator light is used to indicate that the timer has been programmed and is in the automatic mode. Means are provided that permits the timer to be in its automatic mode only if a 24 hour program has been completely stored in the memory. Thus the steady-on condition indicates both that there is a complete program in the memory and the timer is in the automatic mode. The steady-on condition enables the user to quickly check his timer prior to leaving his dwelling since that is when he is most concerned with having automatic operation of lighting.
It will be noted that the time dial knob is active in clocking the shift register only when the timer is being asynchronously (rapidly) programmed or the program is being reviewed. In accordance with a specific aspect of the invention, to provide the user with feedback that tells him the time dial knob is active, a brief pulsing of the indicator light occurs with each step of the time dial knob rotation. Also, it is preferred that the asynchronous (rapid) program mode is activated only if:
The timer disclosed in our application Ser. No. 22,453, can be programmed automatically by the pattern of operations of the depressible time control knob during the first 24 hours after the timer is turned or by asynchronous manual programming by using the time dial knob as described. This requires means for selecting automatically the real time programming mode if the manual programming mode is not selected. It should be noted that the reason for providing the real-time program mode is primarily because many persons find timer programming a difficult task. This is true whether it is a simple mechanical timer with a rotating clock face or a digital time piece such as an alarm clock or wristwatch. To make certain any person, even a small child, could program the timer of this invention, the real-time program mode was made the easiest to use. To accomplish this, the real-time program mode is automatically entered when the power switch is moved from the OFF/CLEAR position to the ON position. Thus, to program the timer the user merely turns it on and uses the depressible timer dial knob as a contact pushbutton for turning on and off the light circuit involved for a period of 24 hours from the time that the light circuit is first deenergized.
In accordance with an important feature of the present invention, prior to the first time the light circuit is turned on, the indicator light will be flashing to indicate that there are no program markers in the memory and automatic operation is not possible. Upon turning the light circuit involved on for the first time the indicator lamp will go out as in the case during the manual programming, signifying the start of a 24 hour real-time program entry period. At the end of the 24 hour period the program is complete and the timer is automatically placed into the automatic mode. Then the indicator light comes steady-on to signal automatic operation is now possible and serves as a convenient signal that the 24 hour real time program has been entered into the memory.
Since the real time program mode is so easily entered, it was judged to be important to prevent the user from being "locked" into this mode when it was not really his intention. This would most likely occur, for instance, right after the user had installed the timer. (It is anticipated that the timer will most often be installed by the homeowner.) Immediately upon installation it will be the most natural action for the user to test the timer by depressing the time dial knob to see if he had normal manual control of the light. The probability is high that he will want to enter a program immediately using the time dial knob. Therefore, in accordance with another feature of the invention, means is provided to prevent the real time program mode from being "locked-in" until the light circuit is energized for at least one-half hour. This provides a half-hour "play period" during which the user may turn the light circuit on and off without getting locked into the real time program mode. Thus each time the light is turned off in the first half-hour the timer will revert to a "not programmed" mode and the indicator light will resume flashing.
It should be noted, also, that the timer reverts to a non-programmed and light circuit opening mode when power is restored following a prolonged power failure (i.e. greater than 5 minutes). In accordance with another feature of the invention, a power failure of less than 5 minutes will not cause loss of memory because such a loss de-energizes most of the timer circuits except those needed to maintain the memory through a voltage stored across a slowly discharging capacitor in the DC power supply. In prior art timers, when temporary loss of power occurs when the light circuit is energized, the light circuit is maintained when power is restored because the memory markers are then left in memory and the time intervals of the storage locations then represent modified time intervals. With the present invention, the loss of the markers is indicated by a flashing light, indicating the need for reprogramming. Reversion of the "not programmed" mode and automatic entry into the real-time program mode also offers the advantage that the timer will be reprogrammed automatically through normal household activity. Thus, a power failure which occurs when the persons who normally program the timer (for instance, the parents of small children) are away from home for a prolonged period, need not deprive the family of the benefit of automatic light operation because the person in charge of the children is unable to reprogram the timer.
The above and other advantages and features of the invention will become apparent upon making reference to the specification to follow, the claims and the drawings.